Big Boss's effectiveness in the field is heavily influenced by his chosen uniform and equipment loadout. There's no single 'best' build; instead, you should adapt your gear to the mission at hand:

- Stealth Build:
- Uniform: Sneaking Suit (reduces noise, increases CQC power) or appropriate camouflage (Leaf, Tiger Stripe).
- Weapons: Mk. 22 (Tranquilizer Pistol), Mosin Nagant (Tranquilizer Sniper), Stun Grenades.
- Items: Cardboard Box, Smoke Grenades, Fulton Recovery System.
- Strategy: Focus on non-lethal takedowns, avoiding detection, and Fulton recovery.
- Combat Build:
- Uniform: Battle Dress (increased defense, more weapon slots).
- Weapons: M16A1 (Assault Rifle), M60 (Machine Gun), M1 Bazooka (Rocket Launcher), Grenades.
- Items: Rations, First Aid Kits, Supply Marker.
- Strategy: Engage enemies directly, prioritize heavy firepower, and be prepared for sustained firefights.
- Balanced Build:
- Uniform: Battle Dress (for defense) or appropriate camo.
- Weapons: M16A1, Mk. 22, Grenades.
- Items: Rations, Fulton Recovery System, Cardboard Box.
- Strategy: Adapt to situations, using stealth when possible and combat when necessary.
Always check the mission briefing for environmental factors and enemy types to choose the most effective loadout.